Isradipine (PN 200-110), a new dihydropyridine calcium antagonist with slight negative inotropic properties in comparison with nifedipine

The influence of isradipine (PN 200-110), a new dihydropyridine calcium antagonist, in comparison to nifedipine and placebo on hemodynamics and left ventricular function was investigated in patients with coronary artery disease (10 patients in each group). The drugs were infused intravenously within 30 min in a dosage which led to a comparable afterload reduction (nifedipine [N] 2 mg, isradipine [I] 0.5 mg, AOP mean decrease: N, 14.7%, I, 13.1%). Increase of cardiac output (N +12.5%, I +15%) and decrease of systemic vascular resistance (N -29.2%, I -25%) were equal in both groups. Nifedipine caused a significant reflex increase of heart rate (+9.2%, p less than 0.001), which was not present with isradipine. The consequence was a significant decrease of the rate-pressure product with isradipine only (-12.5%, p less than 0.001) and not with nifedipine. Although afterload reduction was equal in both groups, isradipine caused a more pronounced decrease of LV volumes (EDVI: N -10%, I -16%) and an increase of ejection fraction (N +8%, I +14%). A significant increase of dp/dtmax, as a result of the afterload reduction, occurred after isradipine only (+13.5%, p less than 0.001) with no changes of dp/dtmax after nifedipine. Since changes of parameters (preload, afterload, HR, LVSP), which influence dp/dtmax independent of the inotropic state, were equal in both groups, the increase of dp/dtmax after isradipine should be a result of less negative inotropic properties of isradipine compared to nifedipine.